1. Field of the Invention
The present invention relates to a cooling device having a working fluid circulation structure using a capillary, and more particularly, to a cooling device using a capillary pumped loop, which has an increased cooling efficiency by virtue of an improved evaporator.
2. Description of the Related Art
Electronic techniques having been continuously developed in recent years have accomplish the modularization, miniaturization and high-output of electronic equipment. Accordingly, the heat generation rate per unit area in electronic equipment continuously increases. An appropriate control capability with respect to the generated heat of this electronic equipment is an important item to be considered during designing and operation. The temperature of electronic equipment can be controlled by heat conduction, natural convection/radiation or forced convection of air, liquid cooling, immersion cooling, or a heat pipe method.
Capillary pumped loop flow (CPLF) has been first proposed by Stenger of the NASA Lewis center, and Tuckerman and Pease demonstrated that a fine channel cooling method could be used to cool high-heating electronic apparatuses.
FIG. 1 is a schematic configuration view of a cooling device using a CPL, which has been proposed by Stenger. Referring to FIG. 1, a pipe 1 having a working fluid travel path of considerable size forms a loop.
An evaporator 2 is installed on the working fluid travel path of the pipe 1. In the evaporator 2, a porous body 22 is placed within a case 21 to which heat is transmitted from the outside.
The porous body 22 has fine cavities which causes capillarity, such that a working fluid 23 is attracted by the capillarity, and the working fluid within the fine cavities is evaporated by heat absorbed from an external source. Vapor produced by a phase change of the working fluid is discharged in a direction opposite to the direction of introduction of the working fluid 23, and travels through the pipe 1. The vapor is gradually deprived of heat while flowing in the pipe 1, is liquidized after being sufficiently deprived of heat, and travels back toward the evaporator 2.
According to the cooling device having such a configuration, vapor is liquidized while traveling the pipe 1 having a considerable length, and thus bubbles 24 are formed in the pipe 1.
This conventional cooling device using a CPL must be inevitably enlarged, so it is not suitable for small-sized electronic apparatuses. Also, the bubbles lying in a pipe and a working fluid incompletely liquidized between formed bubbles act as resistance against the flow of the entire working fluid.
An objective of the present invention is to provide a cooling device using a capillary pumped loop (CPL), which can become smaller and thinner.
Another objective of the present invention is to provide a cooling device using a CPL, which has a high cooling efficiency even when it is small.
To achieve the first objective, the present invention provides a cooling device using a capillary pumped loop (CPL), including: a lower board having a looped groove formed on the upper surface; an upper board combined with the upper surface of the lower board to cover the groove, so that the flow path of a working fluid is provided; an evaporator which is provided on the flow path, and has a plurality of fine evaporating fins incorporated into the upper or lower board; and a condenser which is provided on the flow path at a predetermined distance apart from the evaporator, and has a plurality of fine condensing fins incorporated into the upper or lower board.
To achieve the second objective, the present invention provides a cooling device using a capillary pumped loop (CPL) including: upper and lower boards for providing a path of travel of a loop-shaped working fluid; an evaporator which is provided on the path of the working fluid, and has a plurality of fine evaporating fins; and a condenser which is provided on the path at a predetermined distance apart from the evaporator, and has a plurality of fine heat absorbing fins.
In the cooling devices of the present invention, preferably, at least one of the evaporating fins and the condensing fins are boards having a predetermined height, which are arranged in strips, or a plurality of micro walls. Here, it is preferable that the micro hexahedral condensing fins have different sizes.
It is also preferable that the cross-section of the inlet of the evaporator is smaller than that of the outlet of the evaporator. Preferably, a first protrusion is formed on the side of the inlet of the evaporator so that the inlet of the evaporator has a smaller cross-section than that of the outlet, and a second protrusion having a predetermined height is installed on the side of the outlet of the evaporator. In particular, it is preferable that the top surface of the second protrusion having a predetermined height from the surface on the side of the outlet of the evaporator is higher than the bottom surface of the first protrusion.
Preferably, a vapor inflow space is provided over the evaporator, and the evaporating fins are installed below the vapor inflow space, and the vapor inflow space of the evaporator becomes wider in the direction of the outlet of the evaporator.